S = input()
dp = [float("-inf"),float("-inf")]
ans = float("inf")

for i,c in enumerate(S):
    if c == "c":
        dp[0] = i
    elif c == "w":
        ans = min(ans,i-dp[1]+1)
        dp[1] = dp[0]

if ans == float("inf"):
    ans = -1
print (ans)